Diabetes is a metabolic disorder syndrome characterized by hyperglycemia. The number of diabetes patients around the world has been increasing at a speed of 6 percent each year. Between 2010 and 2030, the number of adults with diabetes was expected to increase by 69% in developing countries and by 20% in developed countries. Diabetes includes type 1 and type 2 diabetes, with type 2 diabetes accounting more than 90% of all cases of diabetes. There is currently no known method to conquer diabetes, and the patients' conditions are generally controlled and alleviated by orally administered drugs for a long-term. But most of current drugs for diabetes are chemical or biochemical drugs, which have much side effects. Based on this critical situation, safer and more effective treatment modalities for diabetes are therefore needed to address the increase in prevalence of diabetes.
A polysaccharide with hypoglycemic activity was obtained from fruit body of cultivated Grifola frondosa by Xun Ma—α-glucan with a molecular weight of 400-450KD. In the process of isolating polysaccharides from fruit body of Grifola frondosa, Kubo obtained a glycoprotein after adding one volume of ethanol into the hot water extract to generate suspension and centrifugation. The glycoprotein named X-fraction (polysaccharide:protein=65:35), with a molecular weight of 5×105 D, showed a significant hypoglycemic activity. Structure analysis indicated that it was a β-1,6-glucan with α-1,4-branch.
The modern pharmacology studies reveals that blood serum glucose can be lowered through increasing insulin levels, regulating the activity of some enzymes related to glycometabolism and sequentially accelerating the glucose oxidation utilization, and through improving the insulin resistance or inhibition of glucose absorption.
The possible action mechanism of MT-α-glucan from the fruit body of Grifola frondosa was increasing sensitivity of insulin and improving insulin resistance of the surrounding tissue through increasing the number of insulin receptor. Water soluble extract FXM from Grifola frondosa potentially decreased blood serum glucose by improvement the insulin resistance. Glycoprotein SX from fruit body of Grifola frondosa can improve glucose tolerance and increase the body's sensitivity to insulin.
It has been found that Grifola frondosa and its active ingredients have obvious hypoglycemic activity, however, the compositions, structures and mechanisms of most bioactive hypoglycemic ingredients are not fully understood, due to the complex chemical structures. That directly hinders the process of developing new anti-diabetes agents.